We’ve always replaced the toilet seat. I mean, how many unknown butts have been on it? Ewww.
I looked at a house for sale once that was really nice, but it was a no-deal when the toilet seat in the hall bathroom was cracked and peeling. Such an easy fix, and the home owner chose not to do it.

I’m not sure it ever occurred to me to replace them unless they were in disrepair. I’ve only rented so I might have thought differently if I had owned. Now that you’ve planted the idea, I’ll probably buy new ones now. I’ve always sterilized them, not just cleaned, but really sterilized.

While we’re on the subject – I would never keep/use someone else’s mattresses or cloth/leather furniture.